Some network-based computing service providers allow customers to purchase and utilize computer resources, such as virtual machine instances, on a permanent or as-needed basis. In addition to virtual machine instances, such computing service providers typically allow customers to purchase and utilize other types of computer resources. For example, customers might be permitted to purchase access to and use file and block data storage resources, database resources, networking resources, and other types of computer resources. Utilizing these computer resources as building blocks, customers of such a network-based computing service provider can create custom solutions that provide various types of functionality, such as application hosting, backup and storage, content delivery, World Wide Web (“Web”) hosting, enterprise information technology (“IT”) solutions, database services, and others.
When requesting certain types of computer resources, such as virtual machine instances, customers of network-based service providers such as those described above are typically able to specify some generic details about the actual hardware and software platform that is allocated to provide the computer resources. For example, in the case of virtual machine instances, a customer might be permitted to specify the desired amount of processing memory, the desired level of processing capability, and a desired amount of disk storage. The network-based computing service then selects a particular hardware platform, such as a particular server computer, to utilize to instantiate the virtual machine requested by the customer.